CLEO is the name for the particle detector operating at CESR (the Cornell Electron Storage Ring). It is also used in reference to most everybody associated with CESR who happens to be doing research in high energy or particle physics.

CLEO stands for absolutely nothing. Somebody just thought it would be funny in light of CLEOpatra’s historical associations with certain CaESaRs. Ha ha.

CLEO is currently on its fourth life. The past couple decades have seen the rise and fall of CLEO, CLEO II, and CLEO II.V. CLEO III is now up and running with a whole bunch of neat new stuff. The CLEO apparatus consists of a four layer silicon vertex detector, a many-layered drift chamber, a Ring Imaging Cherenkov radiation detector (RICH), and a muon detector.